My build is a couple of years away but I am trying to methodically go through the steps of construction to record standards, methods and prices in order to minimize delays and unexpected costs. I would like to start with foundation requirements and progress accordingly.

Background: My wife and I purchased a parcel of land measuring approximately 13 rai. The property originally contained 4 ponds and a Thai style “thatch roof style barn”. One pond, nearest the roadway, was filled in 2009 in anticipation of the house construction. The soil is mostly a red clayish soil even at a depth of -1.0 - 1.5m depth. When inquiring about the soil load bearing conditions, we were told that piles would most likely be necessary to base our house foundation on. This is where I would like to start.

So the first issue is soil conditions which require piles. My property is very clayish/sandy soil (old rice paddies). I had a local pile distributor come out to our property and suggested 0.18 x 0.18 x 20m piles based on some other builds in the area. ok I can accept that....we'll see how much pile has to be used. I was quoted a price for two sizes of piles. (0.18x0.18x 20m costing 3200 baht each and labor of 1066 baht per pile) & (0.22x0.022x 20m @ 4200 each and labor of 1166 baht ea.) Does this sound acceptable?

Thanks, Rodger. Very valuable information. Added to my to do list. It would be a significant savings if I did not have to follow the recommendations of the local pile producer. I will check next time I return to Thailand as I am not sure how to converse with them online.

So continuing beyond the requirements for piles, the footing requirements exist. If piles are required, footings would be constructed directly on top of the piles. If piles are not necessary, footings must be placed upon soils that provide the appropriate load bearing qualities. As a foundation is the part of a structure which transmits the weight of the structure to the ground, technically you need to know the weight each footing will be supporting. These calculations can be extremely tedious. I believe the norm is to provide 3000 psi for footers.Can anyone verify that a general one story build would require soil that can provide 3000 psi?

Once the load bearing capacity has been verified, one can consider the design of the footing. So I believe the standard in Thailand is to use a 1m x 1m footing pad. The problem is I have seen several variations of the concrete and rebar framing. Some claim a 20cm depth and some a 40cm depth. Some require rebar at 0.25m spacing and some at 14cm spacing. These are based off of other builds in the forum. Does anyone have a true standard for the rebar placement?

Thanks, BKBILL. It looks like your build went with a 0.25cm thickness for the footing pads. The amount of rebar indicated don’t seem to mirror the actual drawing. I do like the fact that the frame extends vertically up the sides of the pad. Many builds in the forum did not do this. The different pad sizes surely correlate to load and soil bearing capacity. One thing I forgot to cover was which I saw on your drawings was the preparation under the pad. I couldn’t read the smaller text on these measurements. I believe one of them is addressing a 0.05 cm “topping” of concrete to provide a clean base. Not sure what the other is describing. Could you provide this information?

So designing the size, depth and amount of rebar for a concrete footing depends on several factors. The amount of weight that will be applied (varies greatly; one story, two story, and types of roofing and wall materials), soil bearing capacity (types and grades) and a truckload of computations. My house will be a single story home so for planning purposes I am using a 1m x 1m x 0.4m footing pad. I’m sure this will be sufficient; maybe overkill. Calculations: 0.4m3 per footing

The amount of reinforcement steel is directly related to the design of the concrete and provides compression and tensile strength. Although I have seen some references to using 9mm smooth (SR) I believe the norm and best practice is to use the 12mm (SD30). Placement of the rebar is yet another calculation.

One reference I found was from a reputable university in the U.S. that stated: Cover of concrete over/under the reinforcement must be provided in order to achieve the full tensile capacity and protect the steel from corrosion. For indoor exposure, 1.5 inch (3.81 cm) is typical for beams and columns, 0.75 inch (1.9 cm) is typical for slabs, and for concrete cast against soil a 3 inch (7.62 cm) minimum is required. The pads are definitely in the ground so I’m using 8cm as the covering depth. There is a calculation for spacing of rebar also. I’m using a 7 x 7 grid with vertical legs which gets me a 14cm spacing.Calculations: approx. 24m per footing

Still waiting on advice on concrete topping to cover the bare soil. If I remember correctly, someone used a gravel as the base.

If anyone has a current for price concrete and 12mm rebar I would appreciate it.

I forgot to post this up front. Here is a current satellite view of the property. Notice the northern end (top) shows that pond #1 was filled in several years ago. it is slightly unparallel with the roadway. This will be eventually be straightened.

Thanks Sometimewoodworker. That's a very big price range. I'm using 1700 m3 as a base price. Does this seem sufficient? I am building in Bang Khla. There are no doubt cement producers in Chachoengsao not far from my home. Most likely where I will buy.

Alan in one of your first posts yo mention twenty meter long piles is that correct it don't remember seeing twenty meter long piles especially that thickness.longest I have seen are about six meter [*]

Sisaketdreaming, I’m quite surprised the forum doesn’t throw more standards around. It would be easier to figure all this out. For my build the garage will be a slab on grade. There are several factors which contribute which I will discuss later. For a garage, a well compacted subsurface, vapor barrier, 4 inches of 3000psi concrete with rebar is fine for car or truck weights. For heavier weights use 5-6 inches of 4-5000psi concrete w/rebar. Design of residential floors are supposed to be based on use and established live and dead loads that will be expected. The remainder of the house will be elevated off the ground and will probably go with the pre-stressed concrete slabs with wire mesh and a top coating. About 4 inches. Truthfully, I have not researched requirements in Thailand except for the pre-stressed slabs. Information is on their websites. I’m relying mostly on U.S. standards and a decent Thai architect when the time comes.